1. Field of the Invention
The present invention relates to a flowswitch; and more particularly to a flowswitch used to monitor and detect the flow or no flow condition of liquids in pipelines.
2. Brief Description of Related Art
Flowswitches are used to monitor and detect the flow or no-flow condition of liquids in pipelines. A flowswitch can make or break an electrical signal when flow or no-flow is detected and is used to actuate a signal when flow stops, start a motor with flow, shut off an alarm when flow is adequate, or stop a motor with no flow. A flowswitch typically has a wetted side that installs into the piping that carries the liquid that will actuate the switch, and a dry side with the electrical connections.
One known flowswitch is shown in FIG. 1 and has a bellows design that has been in the field for over 20 years and customers are familiar with the design. However, disadvantages of this design include the following:
Inconsistent switching points from unit to unit;
Relatively high operating forces required to switch the unit at a minimum setting;
Switching points change as the operating pressure changes;
The bellows may erode from the cleaning solution residue left after the forming and cleaning operations;
The bellows must be soldered to flanges, and solder may contain lead;
The bellows may fail due to metal fatigue as it flexes back and forth; and
Paddle arm may not be aligned with center of base due to bellows deformation.
Moreover, a prior art search was conducted and many different valve devices were found, including the following:
One valve device is actuated by fluid flow having a shaft with an O-ring seal arranged in a housing of the valve. The other end of the shaft is arranged in a recess having no exposure to the outside environment. The shaft has a flat portion for cooperating with a switch button of a switch in a cam-like manner. However, the valve device design has an unbalanced device since the shaft only has an O-ring on one end, and the cam-like relationship between the flat portion and the bottom is likely to contribute to increased friction, especially as the valve device wears.
One fluid flow sensing device has a pair of O-rings arranged in relation to a shaft. However, the O-rings are not arranged in O-ring grooves; therefore, need washers and nuts to holding them in place on the pivot arm in response to pressurized fluid flowing in the piping.
One flow switch has side walls with a shaft passing through and connected to a paddle. The shaft is not coupled to the side walls on either side with an O-ring. The switch is actuated via a magnet and magnetic coupling.
One fluid flow sensing device has walls with a shaft passing through and connected to a vane. The shaft has O-rings and washers that are sufficiently tight to make a fluid-tight seal. The shaft also has a spring washer and nut.
One fluid measuring device has a shaft passing through a central body. The shaft has suitable packing, sleeves and nuts. However, the shaft does not have O-ring grooves for retaining the suitable packing or sleeves.
One fluid responsive switch has a transverse pin arranged in a central frame structure and has a disc coupled thereto via an arm. The pin has an annular resilient material but does not have O-ring grooves.
One spool deflection indicator does not have a shaft with a pendulant paddle for sensing fluid flow that has O-ring grooves for receiving O-rings.
One butterfly valve has a shaft with shaft bearings. Although the main body has grooves not labeled for receiving the bearings, the shaft does not have the same.
One fluid responsive switch pivot arm seal has a pivot arm arranged on a pivot pin with circumferential grooves for receiving an elastomeric material for providing additional bonding between the resilient seal. The pivot arm does not have grooves for receiving the bearings.